Lubricant

ABSTRACT

A lubricating composition is disclosed having improved multifunctional properties and comprises a major amount of an oil of lubricating viscosity and minor amounts of a phenolic or an amine anti-oxidant and a bisphosphoramide having from 30 to 300 carbon atoms.

United States Patent [191 Hotten 51 Sept. 2, 1975 [73] Assignee: Chevron Research Company, San

Francisco, Calif.

22 Filed: on. 9, 1973 21 Appl. No.: 404,573

[52] US. Cl. 252/49.9; 252/46.6; 252/46.7; 252/49.8

[51] Int. Cl. Cl0m l/44;C10m H20 [58] Field of Search 252/498, 49.9, 46.6, 46.7

[56] References Cited UNITED STATES PATENTS 2,574,516 11/1951 Walter et a1. 252/49.9 X

2,632,767 3/1953 Smith et a1 252/49.8 X

2,952,701 9/1960 McConnell et al. 252/49.8 X

3,1 15,464 12/1963 Orloff et al. 252/49.8

3,296,134 1/1967 Lee 252/49.9 3,309,317 3/1967 Wittner et a1 252/49.9 3,476,685 11/1969 Oberender et a1 252/46.7 3,553,131 l/1971 Hepplewhite et 252/46.7 3,778,376 12/1973 Herber 252/49.9 X 3,819,748 6/1974 Dulog et a1. 252/49.9 X

Primary Examinerl-lelen M. S. Sneed Attorney, Agent, or FirmG. F. Magdeburger; C. J. Tonkin 57 ABSTRACT A lubricating composition is disclosed having improved multifunctional properties and comprises a major amount of an oil of lubricating viscosity and minor amounts of a phenolic or an amine anti-oxidant and a bisphosphoramide having'from 30 to 300 carbon atoms.

14 Claims, No Drawings LUBRICANT BACKGROUND OF THE INVENTION This invention relates to an improved lubricating composition. More particularly, this invention relates to a lubricating composition containing an additive combination having improved anti-oxidation and antiwear properties.

Hydrocarbon oils are partially oxidized when contacted with oxygen at elevated temperatures for prolonged periods. The intemal combustion engine is a model oxidator since it contacts a hydrocarbon motor oil with air under agitation and at high temperatures. Moreover, many of the metals (iron, copper, lead, nickel, etc.) manufactured into the engine and in contact with both the oil and air are excellent oxidation catalysts which effectively increase the rate of oxidation. The oxidation of motor oils is particularly acute in the modern internal combustion engine which is designed to operate under heavy work loads and at elevated temperatures.

The oxidation produces acidic bodies within the motor oil which are corrosive to typical copper-lead and cadmium engine bearings. It has also been discovered that the oxidation of the oil additionally contributes to piston ring sticking, the formation of sludges within the motor oil and an overall break-down of the viscosity characteristics of the lubricant.

Several effective oxidation inhibitors have been developed by the lubricant industries and their employment has been utilized in almost all of the conventional motor oils today. Typical of these inhibitors are the phenolic anti-oxidants, such as the sterically hindered phenols, thio benzoic acid esters, etc., and amine antioxidants such as alkylated phenyl amines, alkyl phenolformaldehyde-amine poly condensates, etc. These inhibitors, while exhibiting excellent anti-oxidation properties, are burdened by economic and compatibility problems. A need therefore exists for an improved antioxidant that is stable at elevated temperatures, that can be employed at reduced concentrations, that is economical and that is relatively easy to produce.

It is therefore an object of this invention to provide an improved lubricating composition.

It is an additional object of this invention to provide a lubricant composition having improved antioxidation properties.

It is another object of this invention to provide a lubricant composition containing an anti-oxidant.

A further object of this invention is to provide a method of inhibiting oxidation of a motor oil.

Other additional objects will become apparent from the following description of the invention and accompanying claims.

SUMMARY OF THE INVENTION The aforegoing objects and their attendant advantages can be realized by incorporating into a major portion of an oil of lubricating viscosity a combination of (1) an oil-soluble phenolic or aromatic amine antioxidant and (2) a bisphosphoramide having from 30 to 300 carbon atoms.

I have discovered that the anti-oxidation and other properties such as anti-wear, etc., of a lubricant containing a conventional phenolic or aromatic amine oxidant can be increased by the addition of a bisphos- "phoramide activator. Although the exact mechanism of the bisphosphoramide in promoting the anti-oxidation properties of the phenolic and aromatic amine additives is unknown, I have found that the two compounds complement each other in a synergistic manner resulting in a combination having properties superior to either additive alone.

With the instant combination, the amount of the phenolic or aromatic amine anti-oxidant necessary in order to impart the desired properties to a lubricating oil, functional fluid or industrial oil blend is significantly less than that amount needed when the bisphosphoramide component is not present.

DETAILED DESCRIPTION OF THE INVENTION The compositions of this invention are highly stable lubricants and exhibit excellent oxidation stability and display good anti-wear properties. These lubricants are quite useful in motor oils for internal combustion engines, particularly in gasoline engines operated under elevated temperature conditions and for gear oils and industrial lubricants. These lubricants may also be used in rotary engines, transmission fluids, hydraulic systems, turbines, etc.

The lubricant composition of this invention having improved anti-oxidation and anti-wear properties comprises (l from to about 99 parts by weight of a stable organic oil and of lubricating viscosity, (2) from 0.1 to 5 parts by weight of an organic oil-soluble phenolic or aromatic amine anti-oxidant and (3) from 0.05 to 1 parts by weight of a bisphosphoramide containing from 30 to 300 carbons. The ratio of the anti-oxidant component to the bisphosphoramide normally varies from 1 to 20:1 and preferably from 5 to 15:1.

ANTI-OXIDANT COMPONENT The class of anti-oxidants which may be employed in the practice of this invention include oil-soluble phenolic anti-oxidants and oil-soluble aromatic amine antioxidants. Included within the definition of phenolic anti-oxidants are sterically hindered phenolics such as hindered phenols 'and bisphenols, hindered 4,4- thiobis-phenols, hindered 4-hydroxy and 4-thiolbenzoic acid esters and dithio esters, and hindered bis(4-hydroxyand 4-thiol-benzoic acid and dithio acid) alkylene esters. The sterically hindered phenols and benzoic acid esters are the preferred phenolic antioxidants.

The sterically hindered phenolics have the basic groups wherein:

X is sulfur or oxygen and preferably oxygen; R and R are alkyl groups which sterically hinder the XI-I group and preferably have from 4 to 10 carbons and usually branched chain;

R and R are the same or different constituent selected from hydrogen or a C C alkyl and preferably hydrogen; and

A is defined infra.

The phenolic moiety is substituted in both positions ortho to the hydroxy or thiol groups with alkyl groups which sterically hinder these groups. Such alkyl substituents usually have 3 to carbons and one generally branched rather than straight chain, e.g., t-butyl, tamyl, and the like.

The first group of hindered phenolic antioxidants is the single hindered phenols, i.e., where A in the above formula is hydrogen or a C to C alkyl group. Examples of such compounds include 2,6-di-tertbutylphenol, 2,6-di-tert-butyl-p-cresol, 2,6-di-tertamyl-p-cresol; 2-tert-butyl-6-tert-amyl-p-cresol, etc. Trialkylated monohydroxy phenols which may be employed herein are disclosed in US. Pat. No. 2,265,582.

A second group of hindered phenolic anti-oxidants is the hindered bis-phenols. In this case, A is a bond to another basic phenolic group preferably through an intervening C to C alkylene group. Examples of these compounds include 4,4-methylene bis( 2,6-di-tert-butyl phenol), 4,4'-dimethylene bis(2,6-di-tert-butyl phenol), 4,4-trimethylene bis (2,2-di-tert-amyl phenol), 4,4-trimethylene bis(2,6-di-tert-butyl phenol), etc.

A fourth group of hindered phenolic anti-oxidants are 4-hydroxy and 4-thiol-benzoic monothio or dithiobenzoic acid esters, i.e., A in the above formula is a C C ester or a dithio ester group. Exemplary compounds of this group include 3,5,-di-t-butyl-4-hydroxy benzoic acid methyl ester, 3,5-di-t-butyl-4-hydroxy dithiobenzoic acid methyl ester, 3,5-di-t-butyl-4-hydroxy benzoic acid noctyl ester, 3,5-di-t-butyl-4-hydroxyl dithiobenzoic acid n-octyl ester, 3,5-di-t-butyl-4-thiol dithiobenzoic acid n-octyl ester, 3,5-di-t-butyl-4-hydroxy dithiobenzoic acid hydroxypropylene oxypropylene ester, etc.

Another group of hindered phenolic anti-oxidants are bis(4-hydroxyor 4-thiol-benzoic acid or dithiobenzoic acid) alkylene esters, i.e., A in the above formula is a C C di-ester or dithio ester connected through an alkylene linkage to another phenolic group. Exemplary compounds of this type include his (3,5-di-tbutyl-4-hydroxy dithiobenzoic acid) methylene ester, bis(3,5-di-t-butyl-4-hydroxydithiobenzoic acid) ethylene ester, etc. The preparation of these compounds is the same as set forth above, except that the monohalo hydrocarbon is replaced with a dihalohydrocarbon.

Included within the definition of oil-soluble aromatic amine anti-oxidents are amino phenols, naphthylphenyl amines, phenyl alkyl amines, etc. The preferred aromatic amines have the basic group 0 L R. R6

wherein Y is the same or different constituent selected from OH, SH, H, R, NHR or NHR R is the same or different constituent selected from H, or a C to C alkyl, and

R is hydrogen or a C, to C alkyl.

Examples of aromatic amine anti-oxidants included within the above formula include the hydroxyl and thiol amines, such as N-n-butyl-p-amino phenol, N-ethylsec-butyl-p-amino-phenol, N-n-butyl-p-amino thiophenol, N-n-butyl-p-amino-2-methylphenol, the phenylene diamines such as N,N'-di-sec-butylphenylene diamine, N,N'-bis( l ,4-dimethylpentyl)-pphenylenediamine, N,N-diphenyl-p-phenylene diamine, N,N-di-p-naphthyl-p-phenylene diamine, N,N- methyl-ethyl-p-phenylenediamine, N,N-di-n-butyl-pphenylenediamine, etc., the naphthylamines such as N-phenyl-oz-napthylamine, Nphenyl-B-naphthylamine, N-p-methylphenyl-a-naphthylamine, etc., and the diphenylamines such as di-sec-butyldiphenylamine, di-isobornyl-di-phenylamine, and dioctyldiphenylamine.

These anti-oxidants can be prepared by known processes and many of them are commercially available. Because these processes are well known in the art, a description thereof is not necessary.

The Bisphosphoramide The second component of the lubricant composition of this invention is a bisphosphoramide having from 30 to 300 carbons. These compounds are prepared by reacting a difunctional secondary amine or alcohol with phosphorus oxychloride and a monofunctional amine, alcohol or mercaptan. it is believed that the compounds have a generalized structural formula as follows:

(P ar-(Ra wherein X is the same or different element selected from nitrogen or oxygen;

Y is the same or different element selected from oxygen, sulfur or nitrogen when X is nitrogen or nitrogen when both Xs are oxygen;

n is an integer equal to 1 when Y is oxygen or sulfur and 2 when Y is nitrogen;

m is an integer equal to n-l i.e., 0 when X is oxygen and 1 when X is nitrogen;

R is a hydrocarbylene or dihydrocarbylene having from 2 to 18 carbons and preferably from 2 to 8 carbons;

R is the same or different constituent selected from hydrogen when Y is nitrogen or a hydrocarbyl having from l to 24 carbons and preferably from 6 to 20 carbons; and

R is the same or different hydrocarbyl having l to 24 carbons or a hydrocarbylene having from 1 to 18 carbons and preferably from 2 to 8 carbons with one end of each R bonding to the other R or to said R when R is a dihydrocarbylene.

As referred to herein, hydrocarbyl is a monovalent organic radical composed essentially of hydrogen and carbon and may be aliphatic, aromatic, or alicyclic or combinations thereof; e.g., aralkyl, alkyl, aryl, cycloalkyl, alkylcycloalkyl, etc., and may be saturated or ethylenically unsaturated (one or more double bonded carbons, conjugated or nonconjugated). The preferred hydrocarbyl is an alkyl. The hydrocarbylene, as defined herein, is a divalent hydrocarbon radical which may be aliphatic, alicyclic, aromatic or combinations thereof; e.g., alkylene, arylene, alkylarylene, aralkylene, alkylcycloalkylene, cycloalkylarylene, etc., having its two free valences on different carbon atoms. The preferred hydrocarbylene is an alkylene. The dihydrocarbylene, as defined herein is a quadruple valent hydrocarbon radical which may be aliphatic, alicyclic, aromatic or combinations thereof; e.g., dialkylene, diarylene, dialkylarylene, diaralkylene, dicycloalkylene, etc., having less than three of its free valences on a single carbon atom and preferably having its four free valences on different carbon atoms.

The various R, R and R groups as referred to herein include the various derivatives thereof which include the functional groups halo, keto, t-amino, amido, mono-nitro, alkoxy and alkyleneoxy on or within the R, R or R chain with less than 30 percent and preferably less than 5 percent of the available sites substituted.

The above structural formula represents a simplified version of the reaction product. The reaction product is not a pure compound having only one single structure, but, rather, is a mixture of numerous amidophosphorous compounds. The above formula indicates that there are two phosphorus atoms in each molecule. However, because the composition is a mixture of compounds, it is recognized that some molecules may have more than two phosphorus atoms such as polyphosphoramides and at the same time some molecules may have only one phosphorus atom as in monophosphoramide. The reaction product also contains some unreplaced chlorine and such has been detected in the bisphosphoramide product. Thus, it is apparent that while the above chemical equation represents a general description of the reaction product, it should not be interpreted as limiting the invention to the exact structure as shown.

Exemplary bisphosphoramides which may be employed in the practice of this invention include piperazine bis(tetracocophosphoramide); piperazine bis(tetralaurylphosphoramide); piperazine bis(tetramyristylphosphoramide); piperazine bis(dicocophosphoramide); piperazine bis(dilaurylphosphoramide); piperazine bis(tetracocophosphorthioamide); piperazine bis- (tetralaurylphosphorothioamide) piperazine bis(diethyldicyclohexylphosphorothioamide); trimethylene dipiperazine bis(tetracocophosphoramide); diethylene glycol bis(tetracocophosphoramide); N,N-diethyl-l ,3- propanediamine bis(tetracocophosphoramide); piperazine bis(dilaurylphosphorthioamide); etc.

The bisphosphoramides are prepared by reacting phosphorus oxychloride with a difunctional secondary amine or glycol and a monofunctional amine, alcohol or mercaptan. The reaction can be conducted noncatalytically by merely contacting the three reactants within a suitable reaction vessel at a temperature from 0 to 200C and preferably from 20 to C. The reaction pressure is not critical except that it is preferred to apply sufficient pressure on the system to maintain liquid phase conditions. Generally, the pressure will range from 10 to 500 psia and preferably from 14 to 35 psia.

The difunctional amine or alcohol forms the bridging group between the two phosphorus atoms as shown in the structural formula supra. The monofunctional amine, alcohol or mercaptan, on the other hand, reacts with remaining halogens on the phosphorus oxychloride molecules to form the four terminal groups extending from the phosphorus atoms.

The difunctional compounds which may be employed in the practice of this invention have the following general structure:

The definition of X, R, R and m is presented supra under the description of the bisphosphoramide general formula. The dotted lines above illustrate the possible heterocyclic bonding of the R and R groups when X is nitrogen. For example, when R is a dihydrocarbylene or substituted dihydrocarbylene, the two R groups bond to the center R group along path (1 Exemplary compounds of this structure include methylenedipiperazine, dimethylenedipiperazine, trimethylenedipiperazine tetramethylenedipiperazine, diethyleneoxydipiperazine, bis(diethyleneoxy) dipiperazine, etc. When R is a hydrocarbylene, one R group along path (2) forms a heterocyclic ring encompassing the two X atoms. Exemplary compounds of this structure include piperazine, 2,5-dichloropiperazine, 2,5-dimethylpiperazine, etc.

Secondary diamines other than heterocyclic diamines may also be employed in the practice of this invention. In this embodiment, the R groups are hydrocarbyl or substituted hydrocarbyl radicals and R is a hydrocarbylene or substituted hydrocarbylene. Exemplary compounds of this type include N,Ndiphenylethylenediamine, N,N'-diethyl-o-tolidine, N,N-diethylo-dianisidine, N,N'-diethyl-l ,3-propanediamine, N,N'- di(p-chlorophenyl)ethylenediamine, N,N'-diethylcyclohexylenediamine, etc.

Difunctional compounds having two hydroxy groups (X in the above formula is oxygen) include C to C primary diols such as trimethylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tetramethylene glycol, npropane-1,3-diol, 2-butenel ,4-diol, 2,2 thiodiethanol, neopentyl glycol, hydroquinone, chlorohydroquinone, naphthohydroquinone, phenyl-l,2- ethanediol, 2-anilinol ,4-naphthohydroquinone, 2,7-dihydroxynaphthalene, etc, The preferred difunctional hydroxy reactants have from 2 to 12 carbons.

Difunctional compounds having one hydroxy group and one secondary amine group may also be employed.

wherein R,, n and Y are defined supra under the de scription of the bisphosphoramide general formula. Exemplary monofunctional compounds include C to C monohydroxy alcohols, monomercaptans and primary or secondary monoamines. Exemplary monohydroxy alcohols include, methanol, propanol, butanol, pentanol, hexanol, octanol, cyclohexanol, Z-methyl cyclohexanol, phenol, cresol, naphthol, p-chlorophenol, pmethylphenol, etc. Exemplary mercaptans include methyl mercaptan, propyl mercaptan, butyl mercaptan, hexyl mercaptan, cyclohexyl mercaptan, a-naphthylmercaptan, p-butylphenyl mercaptan, ,B-naphthyl mercaptan, etc. Exemplary monoamines include primary alkylamines such as heptylamine, octylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, etc; secondary alkylamines such as, diheptylamine, N-ethyl-N-hexylamine, N-hexyl-N- octylamine, N, N-dioctylamine, and N-butyl-N- hexylamine, etc.; primary and secondary alkylcycloaklyamines and alkylcycloalkyl such as 2-ethylcyclohexylamine, N-ethyl-N-cyclohexylamine, N-methyl-N- cyclohexylamine, N-propyl-N-cyclohexylamine, N,N- dicyclohexylamine, N,-ethyl-N-cyclopentylamine, 2- propyl-3-ethylcyclohexylamine, etc.; and primary and secondary aryl and alkylarylamines such as methylaniline, toluidine, N-ethyl-N-phenylamine, p-anisidine, nitroaniline, diphenylamines, N,N-propylphenylamine, 2,4,6 trichloroaniline, N-octyl-N-phenylamine, pphenetidine, etc.

Particularly preferred monohydroxy alcohols, mono mercaptans and monoamines are prepared from animal and vegetable oils and fats. Typical natural oils and fats which may be employed in preparing the monofunctional compounds include coconut oil, corn oil, rape oil, castor oil, peanut oil, cottonseed oil, linseed oil, olive oil, palm oil, safflower oil, soybean oil, tall oil, sperm oil, tallow, lard, etc. These oils are generally comprised of a mixture of saturated and unsaturated fatty acids such as caprylic, capric, lauric, myristic, palmitic, stearic, arachidic, palmitoleic, oleic, ricinoleic, linoleic, eleostearic, etc. The fatty acids are converted into the corresponding primary or secondary amine, alcohol or mercaptan by conventional processing means.

The preferred monofunctional compounds are the C -C primary and secondary vegetable oil amines such as caprylamine, dicaprylamine, laurylamine, dilaurylamine, myristylamine, dimyristylamine, palmi-tylamine, dipalmitylamine, etc. and mixtures thereof.

The preferred bisphosphoramides of this invention are prepared by reacting a primary or secondary monoamine having from 2 to 40 carbons with piperazine and phosphorus oxychloride. The compounds have the following general structure:

wherein R is hydrogen or preferably a hydrocarbyl having from 2 to 20 carbons; and

R, is a hydrocarbyl having from 2 to 20 carbons.

The bisphosphoramides may be prepared by either a batch or continuous processing scheme. In a typical batch process, a reaction vessel, preferably constructed or lined with a corrosive resistant material such as glass, teflon, etc., is charged with a suitable inert reaction solvent and the difunctional and monofunctional compounds. The contents of the reactor are stirred to disperse the reactants within the reaction solvent. The phosphorus oxychloride is then introduced into the reaction vessel in contact with the other reactants. The reaction takes place spontaneously upon the contracting of these reactants to produce the bisphosphoramide. Since the reaction is also exothermic, care must be taken in the introduction of the reactants in order to avoid rapid increases in localized temperatures. Preferably, the phosphorus reactant is introduced into the vessel at a rate of 5 to 25 mols per 50 mols of difunctional and monofunctional compounds per hour. This addition rate is not critical to the practice of this invention and only provides a convenient method of introducing the phosphorus reactant into the system without in another alternative embodiment, the reactants may be charged to the vessel in an intermittent manner. The reaction can also be conducted adiabatically with the heat of reaction effecting the necessary temperature increase in the system.

In preferred embodiments, when a mercaptan or alcohol monofunctional reactant is employed, these compounds are contacted with the phosphorus oxychloride prior to the introduction of the difunctional amine or at least before the stoichiometric amounts of difunctional amine is introduced into the reaction medium. In this manner, the less reactive mercaptan or alcohol is allowed to partially react with the phosphorus oxychloride prior to the introduction of the more reactive difunctional amine. When a dihydroxy difunctional reactant and amine monofunctional reactants are employed, it is, likewise, preferred to introduce the less reactive dihydroxy reactant into contact with the phosphorus oxychloride prior to the addition of the amine reactant.

During the course of the reaction, hydrogen chloride is released as a by-product. This by-product can be stripped from the reaction medium during or after the completion of the reaction. While stripping may be a convenient method for removing the material, the conditions employed during the stripping steps in many instances have an adverse effect on the product bisphosphoramide. Therefore, it is preferred to complex or neutralize the hydrogen chloride within the reaction medium concomitant with its formation. I have found that the complexing or neutralization step can be accomplished by admixing a stable basic compound or acid acceptor within the reaction medium. Exemplary acid acceptors include C to C trialkyl amines such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, etc., basic hetarenes, such as pyridine, quinoline, picoline, pyrazine, etc., as well as basic metal compounds such as magnesium oxide, calcium oxide, calcium carbonate, magnesium carbonate, alkaline earth metal hydroxides such as magnesium hydroxide, calcium hydroxide, barium hydroxide, etc., and alkali hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide or alkali carbonate or bicarbonate.

The preferred acid acceptors are the trialkylamines and hetarenes since water is not produced in the neutralization of the hydrogen chloride by-product. The presence of water in the system is to be avoided since it may react with the phosphorus oxychloride reactant.

The crude bisphosphoramide can then be filtered to remove the liquid reaction medium and unreacted reactants. Although filtering is preferred, it is recognized that alternative purification steps can be performed such as extraction, stripping, etc.

As discussed supra, the reaction is preferably conducted in the presence of an inert stable reaction solvent. Exemplary reaction solvents which may be employed in the practice of this invention include C,=, to C20 aliphatic or aromatic hydrocarbons such as hexane, octane, nonane, benzene, toluene, naphthalene, ethylcyclohexane, etc., halogenated hydrocarbons, hydrocarbon esters, hydrocarbon ethers, etc., may be employed.

The concentration of the various reactants within the reaction medium can vary over a wide range depending upon the reactants chosen, the reaction conditions, vessel construction, processing scheme, etc. Generally, however, the reactants will be present in the amounts shown in the following Table 1.

-'Bused on the amount introduced into the reaction medium.

The molar ratio of the reactants introduced into the reaction medium will generally vary from 3 to 5 mols of monofunctional compound and 0.4 to 0.6 mols of difunctional compound per mol of phosphorus compound. Preferably the reactants are present in substantially stoichiometric amounts.

The lubricant composition is prepared by simply admixing through conventional dispersing techniques, the appropriate amount of oil-soluble phenolic or aromatic amine anti-oxidant, and bis-phosphoramide within a suitable lubricating oil. The selection of the particular base oil, anti-oxidant and bisphosphoramide, as well as the amounts and ratios each, depends upon the contemplated application of the lubricant and the presence of other additives. Generally, however, the amount of oil-soluble anti-oxidant employed in the lubricating oil will vary from 0.5 to and usually from 1 to 6 weight percent in most applications and the bisphosphoramide will range from 0.05 to 5 and usually from 0.1 to 1 weight percent based on the weight of the final composition. The ratio of organic oil-soluble anti-oxidant to bis-phosphoramide will generally vary from 2 to 30:1

" and usually from 5 to :1.

The lubricating oil which may be employed in the practice of this invention includes a wide variety of hydrocarbon oils such as naphthenic-base, paraffin-base and mixed-base oils. Other oils include lubricating oils derived from coal products and synthetic oils, e.g., alkylene polymers (such as, polypropylene, butylene, etc. and mixtures thereof) alkylene oxide-type polymers (e.g. alkylene oxide polymers prepared by polymerizing alkylene oxide such as ethylene oxide, propylene oxide etc., in the presence of water or alcohol, e.g. ethyl alcohol), carboxylic acid esters (e.g. those which were prepared by esterifying carboxylic acids such as adipic acid, azelaic acid, suberic acid, sebacic acid, alkenylsuccinic acid, fumaric acid, maleic acid, etc., with the alcohol such as butyl alcohol, hexyl alcohol, 2- ethylhexyl alcohol, pentaerythritol, etc., liquid esters of phosphorus, such as trialkyl phosphate (tributyl phosphate), dialkylaryl phosphate, triaryl phosphate (tricresyl phosphate) etc. alkylbenzenes, polyphenyls (e.g., biphenyls and terphenyls), alkylbiphenyl/ethers, esters and polymers of silicon, e.g., tetraethyl silicate, tetraisopropyl silicate, hexyl(4-methyl-2-pentoxy) disilicate, poly(methyl)siloxane and poly(methylphenyl) siloxane, etc. The lubricating oils may be used individually or in combinations whenever miscible or whenever made so by use of mutual solvents. The lubricating oils generally have a viscosity which ranges from 50 to 5000 SUS (Saybolt Universal Seconds) and usually from 100 to 1500 SUS at 100F.

In addition to the phenolic and aromatic amine antioxidants and the bisphosphoramide, other additives may be successfully employed within the lubricating composition of this invention without affecting its high stability and performance over a wide temperature scale. One type of additive which may be employed is a rust inhibitor. The rust inhibitor is employed in all types of lubricants to suppress the formation of rust on the surface of metallic parts. Exemplary rust inhibitors include, sodium nitrite, alkenylsuccinic acids and derivatives thereof, alkylthio-acetic acid and derivatives thereof, substituted imidazoles, amine phosphates, etc.

Other types of lubricating oil additives which may be employed in the practice of this invention include antifoam agents (e.g., silicones, organic copolymers), stabilizers, anti-stain agents, tackiness agents, anti-chatter agents, dropping point improvers, anti-Squawk agents, lubricant color correctors, extreme pressure agents, odor control agents, dispersants, detergents, anti-wear agents, such as tricrescyl phosphate and zinc dithiophosphate esters, etc.

In many instances it may be advantageous to form concentrates of the anit-oxidant and the bisphosphoramide with or without a carrier liquid. The employment of concentrates provides a convenient method of handling and transporting the compounds for their subsequent dilution and use. The concentration of the two components within the concentrates may vary from 25 to 99 weight percent of the anti-oxidant, l to 20 weight percent bisphosphoramide and 0 to 45 percent diluent oil, although it is preferred to maintain the concentration between about 40 and weight percent organic anti-oxidant, 5 to 20 weight percent bisphosphoramide and O to 20 weight percent diluent oil.

LUBRICANT PERFORMANCE The presence of the bisphosphoramide within the lubricant composition promotes the anti-oxidation properties of the phenolic and aromatic amine antioxidants. With this combination, less of the antioxidant is necessary in the lubricant to realize the desired anti-oxidation properties.

In addition to promoting the anti-oxidation properties of the phenolic and aromatic amine anti-oxidants, the bisphosphoramides impart substantial anti-wear properties to the lubricant and in many instances surpass the anti-wear properties imparted by tricresyl phosphate and zinc dihydrocarbyldithiophosphate.

It should be well recognized that the anti-oxidant and bisphosphoramide mixture may be successfully employed in lubricant applications wherein oxidation, or metal wear is a problem. Thus, the mixture may be employed in lubricating oil such as motor oils, turbine oils, gear oils, railroad diesel engine oils, tractor and truck diesel engine oils, two cycle gasoline engine oil, cutting oils, drilling oils, lapping, grinding and honing oils, lubricating oils for pneumatic devices such as jackhammers, sinkers, stoppers, drifters and down hole drills.

The phenolic or aromatic amine anti-oxidants and bisphosphoramide mixture may also be useful in mist lubricants. In a mist lubricating system the lubricant is atomized in a mist generator and carried through conduits by an air stream. The lubricant droplets are coalesced and collected at the lubricant site. Such systems permit simultaneous lubrication of serveral remote lubrication points from a central lubricant reservoir.

The following examples are presented to illustrate the practice of specific embodiments of this invention and should not be interpreted as limitations upon the scope of this invention.

EXAMPLE 1 This example is presented to illustrate the preparation of a representative bisphosphoramide of this invention. A two-liter resin flask equipped with a dropping funnel, gas tube, stirrer and thermometer is charged with 3 g. of toluene, 303 g. of triethylamine, 754 g. of dicocoamine and 43 g. of piperazine. The contents of the flask are stirred and heated to a temperature of 50C to uniformly disperse the dicocoamine and piperazine within the toluene solution. The contents are cooled to 29C and 155 g. of phosphorus oxychloride are slowly added to the mixture through the dropping funnel for a period of approximately one hour. A stream of nitrogen gas is passed through the reaction medium at a rate of about 200 milliliters per minute.

After the phosphorus oxychloride has been charged to the reactor, the contents are heated to reflux at a temperature of approximately 120F for a period of about 1.5 hours. At the end of the reaction period the reactor contents are cooled and filtered to recover the filtrate. The filtrate is then washed with 700 ml. of water until the filtrate is free of chloride. The filtrate is stripped of toluene and the remaining waxy residue is calculated to have the following structural formula:

H II (Coco N) P-N N-P (NCoco where Coco is a mixture of alkyl groups derived from coconut oil fatty acids.

An analysis of the product reveals the following:

This example is presented to demonstrate the preparation of piperazine bis (N,N-diethyl-N,N-dicyclohexylphosphoramide). In the preparation, a 2-liter resin flask equipped with a dropping funnel, gas tube, stirrer and a thermometer is charged with 380 g. of toluene, 606 g. of triethylamine, 5 10 g. of ethylcyclohexylamine and 84 g. of piperazine. The mixture is heated to a temperature of 50C and stirred to disperse the amine reactants within the toluene. Phosphorus oxychloride is then slowly introduced into the reaction medium at a rate of 300 g. per hour. During the addition of the phosphorus oxychloride the mixture is maintained in dry state by passing 200 ml. per minute of nitrogen gas through the reaction medium. After 310 g. of phosphorus oxychloride have been introduced into the vessel, further addition is terminated and the reactor contents are heated to a temperature of approximately C under refluxing conditions. The mixture is refluxed for a period of 2 hours. The flask is then cooled and the contents filtered. The filtrate is washed with water to remove the chloride and thereafter stripped of toluene. The bisphorphoramide product is calculated to have the following structure:

EXAMPLE 3 In this example, diethylene glycol bis(tetracocophosphoramide) is prepared. A one-liter resin flask equipped with a stirrer, turned down condenser, thermometer, dropping funnel and a nitrogen gas inlet tube is charged with 64 grams of triethylamine, 10.6 grams of diethylene glycol, 600 milliliters of toluene and 151 grams of di(hydrogenated coco) amine (mol wt. 377). The mixture is heated to about 50C and stirred to dissolve its reactants within the toluene. Phosphorus oxychloride is then slowly introduced into the vessel, further addition is terminated and the flask is heated to a temperature of l00l 10C under refluxing conditions for a period of about 7 /2 hours. The flask is washed with water to remove the chloride ions and thereafter stripped of toluene. The bisphosphoramide product is calculated to have the following structure.

13 wherein Coco is the coconut oil fatty radical.

An analysis of the bisphosphoramide reveals the following:

Calculated Found (weight 7:) (weight 71) Nitrogen 3.3 3.l6 Phosphorus 3.6 3.8

EXAMPLE 4 0 0 t (Coco N) P N (CH2)3 ill P (N (loco 05 9a 3 CH -cu An analysis of the bisphosphoramide reveals the following:

Calculated Found (weight "/t) (weight 7!) Nitrogen 4.9 3.5 Phosphorus 3.6 3.7

EXAMPLE 5 The procedure of Example I is repeated except that trimethylene dipiperidine is substituted for the piperazine and the following amounts employed.

Grams Moles Trimcthylene 4,4 '-dipiperidine 42 0.2 Triethylamine l l l l l Toluene 500 5O Dicocoamine 302 0.8 Phosphorus oxychloride 62 0.4

The resulting bisphosphoramide is Calculated to have the following structure:

0 V 0 t t EXAMPLE 6 This example is presented to demonstrate the preparation of piperazine bis(tetra-soy-phosphoramide). A 2 liter resin flask equipped with a stirrer, turned down condenser, thermometer, dropping funnel and a nitrogen gas inlet tube is charged with 21.5 grams of piperazine, 510 grams of Armeen 2S[disoyamine- (C, H NH], 152 grams of triethylamine and 1000 ml. of toluene. The contents are stirred and heated to C. 77.5 grams of phosphorus oxychloride are added to the flask over a 2 hour period with the reaction temperature varying from 40 to 60C. After the phosphorus oxychloride has been added, the flask is heated to 6080C for an additional 1.5 hours and thereafter cooled.- The contents are filtered and washed with water and then isopropyl alcohol. The product is then stripped of toluene to yield 489 grams of product. The product is analyzed to reveal 3.02 wt nitrogen and 2.61 wt phosphorus.

EXAMPLE 7 This example is presented to illustrate the effectiveness of the combination of an anti-oxidant and a bisphosphoramide in suppressing oxidation over the use of either component individually. The oxidation test as employed herein measures the resistance of the test sample to oxidation from pure oxygen with a Dorntetype oxygen absorption apparatus (R. W. Dornte, Oxidation of White Oils, Industrial and Engineering Chemistry, Vol. 28, p. 26, 1936). The conditions are atmosphere of pure oxygen exposed to the test oil maintained at a temperature of 340F. The time required for grams of the test sample to remove 1000 ml. of oxygen is observed and reported in the following Table 2.

In order to simulate the oxidation occurring in an internal combustion engine, a mixture of various soluble metal-naphthenates, typifying the metal analysis frequently encountered in crankcase oils, is mixed with the test oil.

The experimental samples subjected to the above oxidation test consist of the following: Sample A contains 97.8 weight percent of a neutral oil having a viscosity of 480 SUS 43C (100F), 2 weight percent of 2,6-di-tbutyl-p-cresol (DBPC) and 0.2 weight percent of a bisphosphoramide prepared by the method of Example 6. Sample B contains 98 weight percent of an identical neutral oil as used in Sample A, and 2 weight percent of 2,6-di-t-butyl-p-cresol (DBPC). Sample C contains 97.8 weight percent of the identical base oil as used in Sample A, 0.2 weight percent of an identical bisphosphoramide as used in Sample A, and 2 weight percent of dibornyl-di-phenyl amine (DBDA'). Sample D con- An analysis of the compound reveals the following:

Calculated Found (weight "/c) (weight 7() 5 Nitrogen 4.6 4.0 Phosphorus 3.4 4.8

tains 98 weight percent of the base oil employed in the above samples and 2 weight percent of dibornyl diphenyl amine. Sample E is 99.8 weight percent of the base oil employed above and 0.2 weight percent of the bisphosphoramide prepared by the method of Example 6. Example F is lOO percent of the base oil employed carbylene.

15 .16 in the above samples. The results of the oxidation test 3. The method defined in claim 1 wherein said diwith the above sample are reported in the following functional. compound is, selected from piperazine, Table 2. methylene dipiperazine, dimethylenepiperazine and trimethylene dipiperazine. 5 4. The composition defined in claim 1 wherein said anti-oxidant is a phenolic anti-oxidant selected from TABLE 2 OXIDATION TEST Oxidation sterically hindered phenols, bisphenols, 4,4-th1o- Sample Additive Package Life (hf) bisphenols, 4-hydroxy; 4-thiobenzoic acid esters and A DBpclbisphosphowmide 42 bis (4-hydroxy or 4-thiol-benzoic acid monoor dithio B DBPC only 2.2 10 acid) alkylene esters.

g gggg ggfis 5. The composition defined in claim 4 wherein said E Bisphosphoramidc only :5 sterically hindered phenolic anti-oxidant has the for- F No additive 0.5

mula:

l5 As can be seen from the above table, the combination increase the oxidation life by approximately fold over the case of the bisphosphoramide only or no additive, and the combination increased the oxidation life by approximately 80-200 percent over the use of the anti-oxidant only. This remarkable demonstration illustrates the unexpected synergism between the two compounds in effecting improved oxidation stability.

1 claim:

1. A composition of matter comprising (A) from 85 to 99 parts by weight of an oil of lubricating viscosity, wherein: (B) from 0.1 to 5 parts by weight of an oil-soluble phenolic or amine anti-oxidant, and (C) from 0.05 to about 1 part by weight of a bisphosphoramide which is prepared by contacting within a liquid phase reaction me- X is sulfur or oxygen; R and R are alkyl groups which sterically hinder the XH group and have from 4 to 10 carbons; R and R are the same or different constituents sedium lected from hydrogen or-a C to C alkyl,

1. phosphorus oxychloride; A 15 selected from hydrogen, a C to C alkyl, a hin- 2. a difunctional compound, having the structure: dered phenol 'thlo hm'fiered P a C2 to C ester, C to C monothio or dithio ester, or a C to C di-ester or C to C dithio ester group. 6. The composition defined in claim 1 wherein said anti-oxidant is an aromatic amine anti-oxidant selected from phenylamines, napthyl-phenyl amines, and phenyl alkyl amines. I I

7. The composition defined in claim 6 wherein said aromatic amine has the formula:

wherein X is the same or different elements selected from ni- 40 trogen or oxygen, R is a hydrocarbylene or dihydrocarbylene having from 2 to 18 carbons, Y e m is an integer equal to 1 when X is nitrogen and O when X is oxygen, 6 "W 6 R is the same or different hydrocarbyl having from l to 24 carbons, or a hydrocarbylene having from R i R l to 18 carbons, with one end of each R hydrocar- 5 0 I3 bylene bonding to the other R hydrocarbylene, or said R, when R is a dihydrocarbylene, and 7 3. a monofunctional compound having the formula: R

wherein Wherein:

Y is the same or different element selected from 1) Rt.- i h me 'or' different constituent selected from oxygen, sulfur or nitrogen when X is nitrogen or or a 1 to 4 l yl,

(2) nitrogen when both Xs are oxygen, R1 is hydrogen or a C to C alkyl, and n is an integer equal to I when Y is oxygen or sulfur Y is the same or different constituent selected from and 2 when Y is nitrogen, OH,.SH, H, R or NHR R is the same or different constituent selected from 8. A composition of matter comprising (1) from hydrogen when Y is nitrogen or a hydrocarbyl havto 99 parts by weight of an oil of lubricating viscosity,

ing from 1 to 24 carbons, (2) from 0.1 to 5 parts by weight of a sterically hinsaid contacting being conducted at a temperature of dered phenolic. anti-oxidant, and (3) from 0.05 to 1 about 20 to C and at a pressure sufficient to mainpart by weight of a bisphosphoramide prepared by retain a liquid reaction medium. 65 acting phosphorus oxychloride with a secondary di- 2. The composition defined in claim 1 wherein said amine with a primary or secondary monoamine.

X is nitrogen, said Y is nitrogen and said R is a hydro- 9. The composition defined in claim 8, wherein secondary diamine is piperazine.

bisphosphoramide formed by reacting phosphorus oxychloride with a secondary diamine and a primary or secondary monoamine.

13. The composition defined in claim 12, wherein said monoamine is a C, C primary or secondary vegetable oil amine.

14. The composition defined in claim 13, wherein said monoamine is di( coco )monoamine. 

1. PHOSPHOROUS OXYCHLORIDE,
 1. A COMPOSITION OF MATTER COMPRISING (A) FROM 85 TO 99 PARTS BY WEIGHT OF AN OIL OF LUBRICATING VISCOSITY, (B) FROM 0.1 TO 5 PARTS BY WEIGHT OF AN OIL-SOLUBLE PHENOLIC OR AMINE ANTIOXIDANT, AND (C) FROM 0.05 TO ABOUT 1 PART BY WEIGHT OF A BISPHOSPHORAMIDE WHICH IS PREPARED BY CONTAINING WITHIN A LIQUID PHASE REACTION MEDIUM
 2. A DIFUNCTIONAL COMPOUND, HAVING THE STRUCTURE:
 2. The composition defined in claim 1 wherein said X is nitrogen, said Y is nitrogen and said R2 is a hydrocarbylene.
 2. a difunctional compound, having the structure:
 3. The method defined in claim 1 wherein said difunctional compound is selected from piperazine, methylene dipiperazine, dimethylenepiperazine and trimethylene dipiperazine.
 3. a monofunctional compound having the formula: (R1)n Y-H wherein Y is the same or different element selected from (1) oxygen, sulfur or nitrogen when X is nitrogen or (2) nitrogen when both X''s are oxygen, n is an integer equal to 1 when Y is oxygen or sulfur and 2 when Y is nitrogen, R1 is the same or different constituent selected from hydrogen when Y is nitrogen or a hydrocarbyl having from 1 to 24 carbons, said contacting being conducted at a temperature of about 20* to 150*C and at a pressure sufficient to maintain a liquid reaction medium.
 3. A MONOFUNCTIONAL COMPOUND HAVING THE FORMULA:
 4. The composition defined in claim 1 wherein said anti-oxidant is a phenolic anti-oxidant selected from sterically hindered phenols, bisphenols, 4,4''-thio-bisphenols, 4-hydroxy; 4-thio-benzoic acid esters and bis(4-hydroxy or 4-thiol-benzoic acid mono- or dithio acid) alkylene esters.
 5. The composition defined in claim 4 wherein said sterically hindered phenolic anti-oxidant has the formula:
 6. The composition defined in claim 1 wherein said anti-oXidant is an aromatic amine anti-oxidant selected from phenylamines, napthyl-phenyl amines, and phenyl alkyl amines.
 7. The composition defined in claim 6 wherein said aromatic amine has the formula:
 8. A composition of matter comprising (1) from 85 to 99 parts by weight of an oil of lubricating viscosity, (2) from 0.1 to 5 parts by weight of a sterically hindered phenolic anti-oxidant, and (3) from 0.05 to 1 part by weight of a bisphosphoramide prepared by reacting phosphorus oxychloride with a secondary diamine with a primary or secondary monoamine.
 9. The composition defined in claim 8, wherein secondary diamine is piperazine.
 10. The composition defined in claim 8, wherein said monoamine is a C10-C30 primary or secondary vegetable oil amine.
 11. The composition defined in claim 10, wherein said monoamine is di(coco)monoamine.
 12. A lubricating composition comprising (1) an oil of lubricating viscosity, (2) an oil-soluble aromatic amine anti-oxidant selected from phenyl amine, naphthyl-phenyl amine, and phenyl alkyl amines, and (3) a bisphosphoramide formed by reacting phosphorus oxychloride with a secondary diamine and a primary or secondary monoamine.
 13. The composition defined in claim 12, wherein said monoamine is a C10-C30 primary or secondary vegetable oil amine.
 14. The composition defined in claim 13, wherein said monoamine is di(coco)monoamine. 